WISEPC J045853.90+643451.9 (designation is abbreviated to WISE 0458+6434) is a binary system of two (A and B) ultracool brown dwarfs of spectral classes T8.5 and T9.5, respectively,[4][5] located in constellation Camelopardalis at approximately 47 ly from Earth.[6]

In early 2011 Mainzer et al. published a paper in The Astrophysical Journal, where they presented discovery of one new found by WISE brown dwarf — ultra-cool object WISE 0458+6434. This object became the first brown dwarf, found by WISE.[2]

Several months later, also in 2011, Kirkpatrick et al. published a paper in The Astrophysical Journal Supplement, where they presented characteristics of 104 first discovered by WISE brown dwarf systems — 98 new found systems and six systems, presented in published earlier papers (one in Mainzer et al. (2011), and five in Burgasser et al. (2011)[7]), among which also was WISE 0458+6434.[1]

WISE 0458+6434 B was discovered in 2011 by Gelino et al., when they examined for binarity nine brown dwarfs using Laser Guide StarAdaptive Optics system (LGS-AO) on Keck II telescope on Mauna Kea; seven of these nine brown dwarfs were also newfound, and two were discovered before, including WISE 0458+6434. These observations had indicated that two of these nine brown dwarfs, including WISE 0458+6434, are binary. Angular separation of WISE 0458+6434 components was 80 mas.[3] Component B is also of late T-type — T9.5[4] (initially was estimated as T9).[3]

Currently the most accurate distance estimate of WISE 0458+6434 is a trigonometric parallax, measured using Spitzer Space Telescope and published in 2013 by Trent Dupuy and Adam Kraus: 0.070 ± 0.019 arcsec, corresponding to a distance 14.3+5.3
−3.0 pc, or 46.6+17.4
−9.9 ly.[6]

According proposed by Cushing et al. in 2011 T/Y transition standard,[9] WISE J0458+6434 B does not relate to Y-type. However, its spectrum has feature similar to those in the spectra of the Y0 dwarfs WISE 1405+5534 and WISE 1738+2732, which were tentatively attributed to NH3 (ammonia) absorption[4][9] — a compelling evidence for NH3 absorption.[4]

^Presented in Gelino et al. (2011), but this is not mentioned in Kirkpatrick et al. (2011) and Kirkpatrick et al. (2012) — according these two articles, the only discovery paper of WISE 0750+2725 is Kirkpatrick et al. (2011).